Endoscopic surgical instruments are often preferred over traditional open surgical devices since a smaller incision tends to reduce the post-operative recovery time and complications. Consequently, significant development has gone into a range of endoscopic surgical instruments that are suitable for precise placement of a distal end effector at a desired surgical site through a cannula of a trocar. These distal end effectors engage the tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.).
Known surgical staplers include an end effector that simultaneously makes a longitudinal incision in tissue and applies lines of staples on opposing sides of the incision. The end effector includes a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway. One of the jaw members supports a staple cartridge that has at least two laterally spaced rows of staples. The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge. The instrument commonly includes a plurality of reciprocating wedges which, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil.
One type of surgical stapling instrument is configured to operate with disposable loading units (DLU's) that are constructed to support a staple cartridge and knife assembly therein. Once the procedure is completed, the entire DLU is discarded. Such instruments that are designed to accommodate DLU's purport to offer the advantage of a “fresh” knife blade for each firing of the instrument. Examples of such surgical stapling apparatuses and DLU's are disclosed in U.S. Pat. No. 5,865,361 to Milliman et al., the disclosure of which is herein incorporated by reference in its entirety.
Some prior disposable loading units have a slot in the bottom of the carrier channel that supports the staple cartridge. A portion of the drive beam that supports the blade extends out through the slot and a support foot or member is attached thereto. Numbered lines are printed on the bottom of the carrier to enable the clinician to ascertain the progress of the blade as it is driven through the staple cartridge. While such arrangement enables the clinician to monitor the firing progress, it requires the clinician to always be able to view the bottom of the carrier channel during the operation. However, because such units are capable of rotating, often times the unit may be oriented in such a way as to prevent viewing of the bottom of the carrier rendering such system useless.
Moreover, prior surgical stapling apparatuses, such as those disclosed in U.S. Pat. No. 5,865,361 and others, lack means that would enable the clinician to quickly ascertain whether the disposable loading unit was previously used. Such prior surgical stapling apparatuses also lack means for determining how many times a handle assembly was used. Those prior apparatuses also lack means for monitoring the amount of firing force that is being generated during the firing process.
Thus, there is a need for a surgical stapling apparatus configured for use with a disposable loading unit and also has means for monitoring the firing progress of the disposable loading unit, regardless of the position of the unit.
There is also a need for a disposable loading unit that is equipped with means for determining whether a disposable loading unit has ever been fired.
There is still another need for a surgical stapling apparatus that employs a disposable loading unit that has means for indicating the number of times that the surgical stapling apparatus has been fired.
Another need exists for a surgical stapling apparatus that has means for indicating the amount of stress experienced by the blade during firing of the instrument.